An optical module used for optical communication includes an optical semiconductor element, which is contained in a package and optically connects to an optical fiber through an optical system. The optical semiconductor element operates when electric power is supplied, and transmits and receives a laser light though the optical system and the optical fiber.
In these days, an optical communication apparatus, like an optical amplifier or a light source for a signal each using the optical module, is requested to reduce mounting size of each optical module in order to reduce size of the apparatus.
Japanese Patent Laid-Open No. 2003-273438 A (hereinafter, Patent document 1) describes a package accommodating an optical semiconductor element connected to an optical fiber, and an optical module with a conductive lead extending toward the outside of the package. The optical module is mounted on a wiring substrate, which includes an opening at the position to which a bottom face of the package is firmly attached. A heat sink is tightly attached to the bottom face of the package through the opening.